Project Summary This application entitled ?Analysis of the impact of missed doses of venous thromboembolism prophylaxis? is in response to the PAR-13-009 Secondary Dataset Analysis in Heart, Lung, and Blood Diseases and Sleep Disorders (R21) program announcement. Venous thromboembolism (VTE) is a common complication for hospitalized patients, affecting more than 750,000 patients and causing over 100,000 deaths each year. Numerous randomized controlled trials (RCTs) have demonstrated the effectiveness of VTE prophylaxis, however real-world clinical practice differs dramatically from structured protocols in RCTs. Despite successful national efforts to improve VTE prophylaxis prescription for hospitalized patients, we have found that prescribing VTE prophylaxis in hospitals does not ensure its administration. We have assembled a database of every dose of pharmacologic VTE prophylaxis prescribed for every patient hospitalized at the Johns Hopkins Hospital since 2008 (~3 million doses), corresponding with the implementation of our electronic health record. By linking this dataset with our complete inpatient registry, we will leverage existing data to determine the association between inconsistent VTE prophylaxis administration and VTE outcomes. We hypothesize that inconsistent administration decreases the protective benefit of prophylaxis and is associated with higher incidence of VTE. We will construct log-binomial generalized estimating equation (GEE) models to determine the dose- response relationship between inconsistent VTE prophylaxis and VTE outcomes. We will include all patients admitted to our hospital between January 1, 2008 and June 30, 2016 in this study, regardless of whether or not VTE prophylaxis was prescribed. These models will study the association between missing a single dose, multiple consecutive doses, multiple intermittent doses, all doses, and no doses of VTE prophylaxis and VTE outcomes. We will control for year, dosing regimen, patient demographics, and known VTE risk factors. Patients who were not prescribed VTE prophylaxis will serve as controls. We hypothesize that inconsistent administration of VTE prophylaxis medications is associated with an increased incidence of hospital associated VTE due to a hypercoagulable rebound effect and that patients are exposed to greater harm by missing doses than by receiving no prophylaxis at all. Successful completion of the proposed research will model the relationship between VTE prophylaxis medication administration and hospital-associated VTE. This research will describe the effectiveness of pharmacologic VTE prophylaxis in real-world clinical practice and generate data that will facilitate the development of novel strategies to optimize VTE prevention in hospitalized patients.